Currently, cardiopulmonary bypass (CPB) system components such as the reservoir, oxygenator, venous air trap, filters, heat exchanger and the centrifugal pump head are all separate items that are co-mounted in proximity or are partially integrated for convenience, efficiency and also to decrease prime volume thereby reducing contact surface area and systemic inflammatory response.
The Terumo Mini-X Reduced Prime Perfusion Circuit is a ‘co-mounted’ bypass system including a reservoir, oxygenator and pump head which are separate units co-mounted and held together by a bracket in close proximity. Another example of a co-mounted system is the Medtronic Resting Heart System.
The Cobe Ideal Mini-Bypass system is a semi-integrated system including an oxygenator, heat exchanger, venous air trap and centrifugal pump head encased in a single unit. The units of a semi-integrated system are generally not individually separable, except for the centrifugal pump head. Another semi-integrated system is the CardioVention CORx® System. These systems do not have an integrated reservoir.
U.S. Pat. No. 6,613,008 to Aboul-Hosn describes a substantially integrated system having a reservoir, oxygenator, heat exchanger, and centrifugal pump head cased in a single unit. However, the system does not include a venous air trap, cannot run as both open and closed systems (i.e., where the blood is open to the atmosphere and where the blood is closed from atmospheric contact), and cannot be used for blood volume sequestration.
Blood volume sequestration is defined as storage of blood pulled from the circuit, whereby such stored blood is no longer in continuity with the circuit blood flow path and/or no longer in constant contact with the circulating blood volume. This is in contrast to conventional blood storage in the reservoir during the procedure, where the so-called ‘stored’ blood volume is actually continuously being drained and replenished, as it is in fluid continuity with the blood flow path in the circuit and/or constantly in contact with the circulating volume.
In addition, for volume sequestration during the case, it has previously been required to use an external shunt line to bypass the reservoir. Volume sequestration using an external shunt line is disclosed in U.S. Ser. No. 10/403,567, filed Mar. 31, 2003, which is hereby incorporated by reference herein in its entirety.
An integrated system with inseparable components should not sacrifice the flexibility and safety associated with dismantlable systems such as ability to run an open or closed circuit, store/sequester volume and have an effective venous air trap to remove air while operating as a closed system that bypasses the reservoir.
Further, there is no currently known system which fully integrates a reservoir, venous-side air trap (venous air trap), a centrifugal head, heat exchanger and oxygenator.